With a paradigm shift to ‘low carbon green growth’, energy savings and greenhouse gas reductions are required in the construction sector. In order to increase the energy efficiency of buildings, high-performance building insulation panels have to be developed.
Currently useful building insulation panels, which are domestically manufactured and sold, are largely classified into organic insulation panels using polystyrene or polyethylene (e.g. Korean Patent Application Publication Nos. 1999-0048791 and 2011-0040347) and inorganic insulation panels resulting from high-temperature melting of ores and then formation thereof into fibers (e.g. Korean Patent Application Publication No. 2003-0058921). Although the organic insulation panels are inexpensive and have high workability, they are problematic because of poor heat resistance and ignition or generation of toxic gases in the event of fires. Also, the inorganic insulation panels rarely ever exhibit thermal insulation performance necessary for high efficiency.
Recently, because of the global eco-friendly and low energy consumption policy stance, the use of vacuum insulation panels is increasing. A vacuum insulation panel (VIP) is a high-efficiency insulation panel manufactured by placing a core material in a sealing member having air tightness and then making the inside thereof into a vacuum state, and may thus manifest thermal insulation performance at least 5˜10 times greater than conventional insulation panels. Such a vacuum insulation panel may be utilized for refrigerators, cold storage warehouses, low-temperature liquefaction tanks, refrigerated containers, hot/cold vending machines, and building panels.
The core material of the vacuum insulation panel is conventionally composed of a polyurethane foam, but this foam is not eco-friendly and may cause a vacuum level to deteriorate due to out-gassing after a long period of time because it is an organic material. Also useful as the core material of the vacuum insulation panel, glass fibers are typically manufactured by a rotary process in such a way that silica, alumina, an alkali metal oxide, an alkaline earth metal oxide, and/or boron oxide are mixed, melted at a high temperature of 1400° C. or more and rotated at high speed using a rotary device such as a spinner to thus undergo a centrifugal force. When the glass fibers are manufactured in this way, an organic binder such as a phenol resin is applied to bonding between the glass fibers. However, such an organic binder is transformed into a gas during or after the vacuum process, and thus the vacuum may become weak, undesirably deteriorating thermal insulation performance of the insulation panel. Furthermore, when the glass fibers are used as the core material, the volume may undesirably increase upon vacuum degradation. As the thickness of the core material is not sufficiently ensured, the amount of glass fibers for the core material is increased, unfavorably increasing the material costs.
Korean Patent No. 10-746989, which is the prior patent of the present applicant, discloses a vacuum insulation panel, which includes needled binderless glass fibers as a core material. Although the needled binderless glass fibers do not cause out-gassing due to an organic material, the core material is oriented in a vertical direction during needling treatment, and thereby thermal insulation performance may become poor and thus does not satisfy the enhanced thermal insulation performance standard. Hence, there is a need to develop a new concept of high-efficiency insulation panels having superior thermal insulation performance with the use of binderless glass fibers, compared to conventional products.